Regex To Match Characters Repeated More Than A Specified Number Of Times

A regular expression that characters repeated more than a specified number of times (9 times in this example).

This can be useful in finding the duplicate characters in a string.

/(.)\1{9,}/

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Explain:

• () Capturing group #1. Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference.
  • . Dot. Matches any character except line breaks.
• \1 Numeric reference. Matches the results of capture group #1.
• {9,} Quantifier. Match 9 or more of the preceding token.

Matches:

• aaaaaaaaaa
• aaaaaaaaaaa
• ==========-

Non-matches:

• aaa
• ababababab

See Also:

• Regular Expression To Check For Repeating Numbers
• Regex To Determine If A String Has All Unique Characters
• Regex To Match Consecutive Occurrences Of The Same Character In A String